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Updated: Nov 19, 2025
Characterization of Human Monocyte Subsets by Whole Blood Flow Cytometry Analysis
Published on: October 17, 2018
Dynamic changes in monocytes subsets in COVID-19 patients
Shuang Qin1, Yujie Jiang1, Xin Wei2
1Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China.
Insights
Critical COVID-19 patients show reduced monocyte counts and impaired antigen presentation, alongside increased pro-inflammatory monocytes. Monocyte HLA-DR expression may help predict severe COVID-19 cases.
Area of Science:
- Immunology
- Virology
- Critical Care Medicine
Background:
- Coronavirus disease 2019 (COVID-19) poses a global health threat.
- Understanding the immunological response in critical COVID-19 is crucial.
Purpose of the Study:
- Investigate monocyte immunological characteristics in critical COVID-19 patients.
- Determine the role of monocyte subsets in COVID-19 pathogenesis.
Main Methods:
- Flow cytometry used to analyze monocyte counts and immune status.
- Study included 32 COVID-19 patients and 18 healthy controls.
Main Results:
- Critical COVID-19 patients had decreased total and CD16- monocytes but increased CD16+ pro-inflammatory monocytes.
- Monocyte antigen presentation (HLA-DR) was suppressed, while inflammatory markers (CD38) were elevated.
- Elevated IL-6 correlated with CD16+ monocytes; IL-6 and IL-10 correlated negatively with HLA-DR.
Conclusions:
- Reduced monocyte HLA-DR expression may cause immunosuppression in critical COVID-19.
- Increased CD16+ monocytes might drive hyperinflammation.
- HLA-DR+ monocytes show potential as predictive biomarkers for severe COVID-19.
Background:
Coronavirus disease 2019 (COVID-19) is affecting the whole world and threatening human health. We aim to investigate the immunological characteristics of monocytes in critical patients with COVID-19.
Methods:
The number and immune status of monocytes were detected by flow cytometry in 32 COVID-19 patients and 18 healthy individuals.
Results:
In critical patients with COVID-19, the absolute number of total monocytes and CD16- monocytes was significantly decreased but CD16+ pro-inflammatory monocytes was increased compared to healthy controls. Antigen presentation potential of monocytes, as measured by HLA-DR expression, was suppressed, while their inflammatory phenotype (CD38 expression) was enhanced. Cytokine levels showed sustained increases in critical patients. And the levels of IL-6 were positively correlated with CD16+ monocytes number. IL-6 and IL-10 levels were negatively correlated with HLA-DR expression of monocytes. During the recovery of COVID-19 patients, the count and immune status of monocyte subsets were restored by degrees. HLA-DR+ monocytes possessed good sensitivity and specificity for predicting the incidence of critical patients with COVID-19.
Conclusions:
In critical patients with COVID-19, decline in number and HLA-DR expression of monocytes might lead to decreased antigen presentation potential and thus immunosuppression, while increased CD16+ pro-inflammatory monocytes might mediate hyperinflammation. HLA-DR+ monocytes might be a meaningful assisted indicator to predict the incidence of critical patients with COVID-19.
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